Modern work machines or vehicles may be powered by electrical propulsion systems. The electrical propulsion systems often include electric drive traction systems that provide driving force to traction devices of the work machines or vehicles operated on high power density batteries. Recently, electric drive traction systems using switched reluctance traction motors have been developed.
Switched reluctance traction motors may have various motor topologies (e.g., the number of stator poles, the number of coils, and the number of rotor poles, etc.). In certain situations, motor topology of a switched reluctance traction motor may be determined based on the number of phases of conduction when supplying direct current (DC) to the motor. A switched reluctance traction motor may have 2 phases, 3 phases, 4 phases, or even more. Generally, a switched reluctance traction motor may have an independent stator pole set associated with each phase of conduction. For example, a switched reluctance traction motor designed to operate on a 4-phase conduction (a 4-phase switched reluctance traction motor) may have 4 sets of independent stator poles. When the total number of the phases increases, the total number of stator poles may also increase. More power may be drawn by the motor, and the complexity of the motor may also increase.
Some switched reluctance traction motors use 3-phase topology, such as described in U.S. Pat. No. 6,717,381 (the '381 patent) issued to Inagaki et al. on Apr. 6, 2004. The '381 patent describes a control device for a 3-phase switched reluctance traction motor. Three-phase switched reluctance traction motors may offer some advantages because the 3-phase motors may use power converters built on standard electronic components. For example, a common building block for most power converters may be an isolated gate bipolar junction transistor (IGBT). IGBTs designed for 3-phase electric induction type motors are considered as standard components and may be available commercially at a low cost.
Three-phase induction type traction motors, however, may still be more costly and less reliable than switched reluctance traction motors under certain circumstances. Two-phase switched reluctance traction motors may be designed to eliminate certain limitations of 3-phase induction type motors. However, power converter components for conventional 2-phase switched reluctance traction motors are often considered as “non-standard” and may not be readily available. Further, conventional 2-phase switched reluctance traction motors may suffer from high torque ripples and may also have dead bands where stator poles and rotor poles are in a particular position or positions such that the motor cannot be started.
Methods and systems consistent with certain features of the disclosed systems are directed to solving one or more of the problems set forth above.